How the Taser Shotgun Shell Works

Ethan Miller/Getty Images The XREP has electrodes on both sides of the nose as well as on the base of the projectile, spreading the effect of NMI.

(c) Ethan Miller/Getty Images

Why do Tasers work? What is it that makes them capable of incapacitating a human, no matter how large or strong that person might be? It all has to do with muscle physiology.

Our bodies work using a combination of electrical and chemical signals to communicate commands from the nervous system to and from our other systems. When we want to flex a muscle, our brain sends electrical signals to special nerve cells. These nerve cells are transducers -- they convert energy from one format into another. In this case, the nerve cell converts the electrical energy from the brain into a c­hemical compound called a neurotransmitter.

­The neurotransmitter tells your muscle cells to contract. On a chemical level, the neurotransmitter causes muscle cells to release calcium within the cell. The calcium binds with the protein troponin, which regulates contraction. Muscle cells work together in huge numbers, making it possible for you to flex a bicep or lift a finger. When the cells stop receiving the command to contract, the calcium returns to a series of intercellular vesicles called the sarcoplasmic reticulum [source: National Skeletal Muscle Research Center].

When you apply a high-voltage, low-amperage electric charge to muscle tissue, it's as if you're overloading its communication system. Taser's electric pulses cause affected muscles to contract up to 19 times per second. Under normal conditions, your body moves by relaxing one set of muscles while contracting another. But if an electronic pulse hits your body, both sets of muscles may try to contract at the same time. Generally speaking, the stronger muscles win out. But because the pulses override the commands from your brain, you have no conscious ability to control their movements.

As a result, the affected area of your body will tense up as the surrounding muscles contract. You may lose your balance and fall. Depending upon where you've been hit, you may not be able to break your fall or catch yourself. That's why people who have been hit by a Taser sometimes suffer superficial cuts, bumps and bruises.

Because Taser uses low-amperage currents, there's little danger of suffering electric burns or more serious side effects. But there's still the potential for complications. While Taser claims the amperage levels are well within safe levels, others aren't convinced. Several individuals have brought lawsuits against Taser charging that the company's product contributed to a person's death.

Until June 2008, Taser either won every case or settled out of court. Taser lost its first case in California -- a jury found the company liable for the death of Robert C. Heston. Police officers hit Heston multiple times with Taser devices while attempting to subdue him in 2005. The jury concluded that the Taser strikes caused Heston's death. The Taser company plans to appeal the decision [source: Johnson].

While the court decision is a setback for Taser, many people depend upon the company's products to provide a solution for situations that don't call for lethal force. It's likely we'll see more controversy as law enforcement and military personnel adopt the XREP in their weapons repertoire. One thing's for certain -- the results will be shocking.

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